In recent years, plastic fuel tanks have also come to be used in general-purpose engines and the like, and known plastic fuel tanks offering a possible solution with respect to environmental pollution are disclosed, for example, in JP-A 2004-52659.
FIG. 5 hereof shows the plastic fuel tank disclosed in JP-A 2004-52659.
Referring to FIG. 5, a coupling member 102 is mounted on a tank assembly 101 in a plastic fuel tank 100. The tank assembly 101 includes a barrier layer 103 constructed from an ethylene/vinyl alcohol copolymer for preventing fuel seepage; an innermost layer 104 laminated onto an interior side of the barrier layer 103, and constructed from polyethylene; and an outermost layer 105 laminated onto an exterior side of the barrier layer 103 and constructed from polyethylene. The fuel would seep to the exterior from inside the tank assembly 101, but is blocked by the barrier layer 103.
It is known that the ethylene/vinyl alcohol copolymer will degrade when exposed to ultraviolet light for a long period of time. For example, there have been instances in which the plastic fuel tank 100 used in general-purpose engines has been bleached by long exposure to ultraviolet light, and the barrier layer 103 constructed from the ethylene/vinyl alcohol copolymer is degraded by ultraviolet light. Specifically, a need exists for a plastic fuel tank that will prevent fuel seepage and be weather resistant with regard to ultraviolet light or the like.